The gen/ directory contains generated *_pb2.py files but there are no .proto source files checked in. Without the sources no one can regenerate or update the generated code.

• Add proto source files to src/sap_cloud_sdk/core/auditlog_ng/proto/ with a
  buf.yaml and buf.gen.yaml that configure output into gen/ and src/buf/.
  (really liked buf btw! Thanks for the suggestion!).

• Also add a Makefile at the repo root with at minimum:

.PHONY: proto
proto:
    cd src/sap_cloud_sdk/core/auditlog_ng/proto && buf generate

• Add .github/workflows/proto-verify.yml that runs
  make proto and then git diff --exit-code to fail the PR if generated files differ.

Let me know if you need any help with all that.